The present invention relates generally to an optical position alignment sensor for aligning electronic components, which is used in the electronic component placement industry. Machines of the type used in the electronic component placement industry are sometimes called pick and place machines.
Electronic shadowing techniques incorporated in optical-based sensors are in widespread use today in the electronics industry in pick and place machines for mounting electronic components on printed circuit boards. One of the most commonly used position alignment sensors is manufactured by CyberOptics Corporation in Golden Valley, Minn. and is sold as a LaserAlign.RTM. component alignment sensor. LaserAlign type sensors use a light source focused into a stripe of light, which is typically incident on the side of an electronic component, thereby forming a shadow which is cast onto a detector. When the electronic component is rotated (by a nozzle controlled in x, y and z direction by the pick and place machine), the shadow cast on the detector changes in width.
The orientation process is generally carried out while the pick and place machine is transporting the component to a target printed circuit for placement. When the orientation process is carried out simultaneously with the transport of the component, the orientation process is sometimes referred to as an "on-head" or an "on-the-fly" measurement. Conversely, "off-head" measurements are made when the sensor is not affixed to the pick and place head but rather, is stationary relative to the head.
One of the problems typically not addressed by the prior art is a position alignment sensor for aligning at least two components which prevents undesirable glints (i.e., reflections), both large and small angle, from interfering with accurately orienting either of the components.